Forgot your password?
Space Technology

Thoughts on the Space Elevator 622

Posted by ScuttleMonkey
from the no-such-thing-as-an-inefficient-government dept.
Keith Curtis writes to tell us that Glenn Reynolds, of Instapundit fame, has posted his thoughts on why NASA should be building a space elevator instead or their current plans. Keith has also posted his throughts from an engineer's perspective (although admittadly still not a rocket scientist). "The challenges are many, but it has been a viable option since carbon nanotubes, structures so strong that one the width of a human hair could lift a car, were invented. A space elevator could be between 10 and 2000 times cheaper than conventional technology and will force NASA to change just about everything they do. Hopefully one day that bureaucracy will wake up and realize it."
This discussion has been archived. No new comments can be posted.

Thoughts on the Space Elevator

Comments Filter:
  • by RUFFyamahaRYDER (887557) <.slashdot. .at.> on Wednesday September 21, 2005 @07:12PM (#13617815) Homepage
    I wonder how long it will take for one of these elevators to reach their destination. If the elevators are going to take a long time they need to be big enough to hold some food and other supplies. I'm sure they will be big enough to send up large equipment though...
  • Hmmm.... (Score:2, Interesting)

    by Chanc_Gorkon (94133) <> on Wednesday September 21, 2005 @07:13PM (#13617821)
    A space elevator will be made of carbon fiber nanotubes correct?? What would be the effect on a hurricane hitting the elevator? Can the string be realed in from one end?? Would it be more prudent to build this in a place far away from a coastline??
  • What about rescues? (Score:3, Interesting)

    by saskboy (600063) on Wednesday September 21, 2005 @07:13PM (#13617823) Homepage Journal
    Why isn't this stuff being used as an emergency rescue material, to make ladders that can be telescoped up to the 30th floor of skyscrapers? Surely there could be less ambitious projects for this material before committing to something that has to deal with the extreme stresses and temperatures in space and the upper atmosphere?

    Make a model of a space ladder/elevator, by designing something that can save lives here at home, and it will take off like a rocket in the public's eye, pardon the pun.
  • by Anonymous Coward on Wednesday September 21, 2005 @07:16PM (#13617851)
    One thing that gets me is the "drop points" that are talked about up the elevator. If you go up 1000ft and let go you drop to the ground. If you let go at 100,000ft, you drop to the ground. only when you have reached the geostationary orbit, (and velocity) will you be able to get off, and "float" in zero gravity,

    Just bugs me all the time,,,,

  • Yes and No (Score:5, Interesting)

    by JaredOfEuropa (526365) on Wednesday September 21, 2005 @07:16PM (#13617854) Journal
    The space elevator seems to be still hovering at that point where it certainly looks to be theoretically feasible, but where no one really has a clear path towards bringing this construct about in reality. (Or is it that there are still a few people laughing at the idea, if you know what I mean?). It seems to me that it would be foolish for NASA to abandon its current plans in favour of this unproven idea, yet it might be wise to throw some money and effort at it.
    It would cost about $6 billion in today's dollars just to complete the structure itself, according to my study
    I've heard a similar figure before, and it's amazingly cheap if you think about it. We, as a silly small country, have blown close to this amount on a couple of utterly useless railroad lines. If we could have had a working space elevator instead...
  • Re:Hmmm.... (Score:2, Interesting)

    by deanoaz (843940) on Wednesday September 21, 2005 @07:20PM (#13617879)
    >>> Would it be more prudent to build this in a place far away from a coastline??

    After reading "Red Mars" I don't think it will matter where you build it. If it comes down it will leave a path of destruction all the way around the Earth's circumference.

    Besides, the termination point needs to be easily accessible or you negate much of the advantage of having the elevator.
  • by RandomPrecision (911416) on Wednesday September 21, 2005 @07:20PM (#13617880)
    "an engineer's perspective (although admittadly still not a rocket scientist)"

    That's even better, because this is an engineering project, not rocketry.

    The first thing that I thought of when I first heard about this is what a great terrorist target it would make. You could shoot at it for many miles around, which might not affect it much if it's as strong as it sounds like the material is, but one would be able to see when it was in use. It's unrealistic to think that people around the world would constantly be taking impudent potshots at anything with any accuracy, but still, it remains a very visible target, and one that would be very difficult to replace.

    On a different note, I see that this would be a social and cultural catalyst. What if we build this elevator in the US, and China wants to use it? It would seem wasteful to demand that China build their own space elevator to do exactly the same. Either we would allow other nations to use the elevator as well, thereby showing at least superficial unity, or we say that we have the world's only space elevator, and if China wants one, they must build their own, which would almost certainly dampen relations.

    I won't speculate on what will happen, but I think either eventual harmony or inevitable conflict would be accelerated by something of this magnitude.

  • by Tango42 (662363) on Wednesday September 21, 2005 @07:32PM (#13617965)
    Actually, it's more than Geosynchronous - the centre of gravity needs to be at GS (or near it, the fact that it's joined to the ground might have an effect), so it has to go past it by an amount depending on the mass of the counterweight.
  • by temojen (678985) on Wednesday September 21, 2005 @07:36PM (#13618007) Journal
    They have high tensile strength, but not high compressive strength. It'd be like trying to push a rope up to the 30th floor.
  • Re:Pixiedust (Score:5, Interesting)

    by AKAImBatman (238306) * <> on Wednesday September 21, 2005 @08:07PM (#13618213) Homepage Journal
    Parent is not a troll. He's trying to make a point. The Space Elevator is a untested and unproven technology. Like all unproven technologies, there are bound to be hidden costs, hidden delays, and hidden engineering problems.

    NASA is taking the correct approach. They are building something that they *know* works first. They can then work out the pixie dust^H^H space elevator next.
  • by dbhankins (688931) on Wednesday September 21, 2005 @08:56PM (#13618496)
    Because angular velocity and rotational velocity are not the same thing.

    The only place where the rotational velocity of a Stalk matches the Earth's (466 m/s) is at the equator where it's tethered. At GEO it's going 3,070 m/s.

    Hurricanes are not so much of a problem. They might tear some of the structures off the sides of the Stalk, but given the cross-section of a Stalk in the face of winds it would encounter and its tensile strength and total mass, the worst a hurricane could do is put a slight oscillation in it, something that stationkeeping thrusters could easily deal with.

    Even if you somehow managed to sever it at ground level or even a few miles up, only the part below the break would wiplash.

    To get a significant planetary wiplash it would have to be severed several hundred or thousand miles up (i.e. in space). Then you're talking about terrorist nukes or a cometary or asteroidal impact. If something made a Stalk wiplash, my money'd be on the terrorist nuke.
  • Re:Pixiedust (Score:5, Interesting)

    by BJZQ8 (644168) on Wednesday September 21, 2005 @09:00PM (#13618515) Homepage Journal
    I agree completely. We've done the moon thing, and have tons of cool rocks. Why do it again? What will that $100 billion do for us that hasn't been done before? It would be much better spent researching and developing something like a 36,000-km nanotube ribbon than going up and getting more rocks. Even if the ribbon proves unproduceable, we would be investing in basic research, and not simply lining the pockets of the US space industry, ie Boeing, Lockheed-Martin, etc. to do something that has been done before.
  • Re:Pixiedust (Score:3, Interesting)

    by TallDave (916610) on Wednesday September 21, 2005 @09:38PM (#13618709) Homepage
    There isn't even really that much basic materials work that needs to be done. They just need to get the composite percentage up (iirc) from around 10% to around 50%. I think the success of carbon nanotube companies and SpaceShipOne suggests the best way to do this is for NASA to offer large monetary rewards, perhaps in the range of $10 - $100M, for producing a workable cable and climber power source. My understanding is those two things are the major engineering hurdles right now. Currently there is a NASA-sponsored climber competition, which I believe has a 400K reward.
  • NASA Bashing (Score:1, Interesting)

    by Anonymous Coward on Wednesday September 21, 2005 @09:40PM (#13618713)
    Suprise, suprise, more NASA bashing. I actually think that Slashdot has a hidden requirement that there are some number of anti-NASA postings per month (or is it per day?)

    Meanwhile, in the real world, here's the way it works. (Just to remind the typical Slashdot reader who rarely visits the place.)

    1. NASA is part of the US government. It is part of a political organization and has to respond to political pressure. This is why mission control is in Texas. This is why there are NASA projects in every state in the union. The NASA budget is PORK. One of the main reasons that NASA gets any funding is to put PORK into the districts of members of congress who vote for it's budget. Bettering human-kind or the technical position of the USA is almost irrelevent to the existance of NASA.

    2. The space elevator is a pure research project at the current time. It is not an engineering task like the Apollo project. At the time of Apollo there were already people in earth orbit. Going to the moon was doing more of the same, only bigger. At the current moment in time there is NO deployable technology to build a space elevator. In rocket terms, it is equivilant to the pre-Goddard era. Yes, carbon nano-tubes exist in the lab, but the longest nano-tube material in existance is a few meters long. No nano-tube structural components exist outside a lab environment. This is why a space elevator is research. To do a space elevator in a specific period of time would be more like the Manhatten project, and that is not going to happen (see point 1 above.)

    3. Going into space is hard. NASA has about as good a track record as any group IN THE WORLD. If NASAs failures seem to be greater it is because they tend to do more projects and have more visibility. You get more press for loosing a mannned unit then for losing a probe, and only Russia and the US are currently in the manned space business. For example, no one is talking about ESA/England loosing the Beagle probes to Mars, but when you talk about the space elevator the subject of shuttle losses is always in peoples minds.

    4. If you want to get people back to the moon or anywhere out of low earth orbit, the only viable choice at the current time is rockets. If you look at the history of the US and USSR/Russian programs, capsules seem to be a better bet then space planes. Capsule technolgy seems to be more cost effective and more reliable. It also makes sense to leverage off existing technology. Using variations of current rockets, like the Solid Rocket Boosters (SRB) and the shuttle main engine reduces both cost and risk and it shortens lead time. It might be better to build single a stage to orbit platform with new engines in the long run, but this would take more time and money to get results. (See point number 1.)

    So it all makes sense if you put it in the right frame of reference. It may not be the smartest plan, but it can work. There are some really signicant problems, but they have nothing to do with space elevators or any other kind of pixie dust. The basic issue is funding. Manned space exploration will distroy the scientific component of NASA. I have heard, for example, that JPL is going to loose a huge number of people. I believe it. Given the Bush administration world view, space only exists for military expolitation and manned missions that are long on propaganda and short on science. Let's face it, there would be no push to go back to the moon if the Chinese did not have a serious commitment to go there. NASA funding is about PORK and politics.

    And to add the final piece of perspecive, the Bush family is really big on unfunded programs that sound really important but to nowhere. The first Bush had a manned Mars mandate, if I remember correctly. The current one has this 'No Child Left Behind' program, which didn't work in Texas and seems to be having even less success at the national level. As long has the press is good, who cares? Guess what will happen to this manned space plan...

  • Re:Pixiedust (Score:2, Interesting)

    by TallDave (916610) on Wednesday September 21, 2005 @09:47PM (#13618744) Homepage
    Space elevators as a real engineering concept are still so new that not many people realize the engineering/materials hurdles are much much closer to being overcome than they were even five years ago, when you could have have stated unequivocally that a space elevator requires large amounts of unobtanium. Five years ago, it was pixie dust. Today, it's probably a challenge more on the order of building a 3Ghz processor circa 1995. And really, why waste all that money going to the moon? Is it supposed to make us all proud of ourselves? I'm not thrilled about being remembered as the generation that went to the moon.. again.
  • "Unobtainium" (Score:3, Interesting)

    by wurp (51446) on Wednesday September 21, 2005 @11:01PM (#13619067) Homepage
    The Wikipedia article [] says otherwise... it says that 65 GPa - 120 GPa are the expected required strengths. And it says that 63 GPa nanotubes have been created, and 120 GPa are theoretically possible.

    It certainly sounds to me as if it's well within the realm of possibility, and that's with no fundamentally new discoveries. The foolish assumption would be that 10 years of research and $100 billion would turn up nothing fundamentally new.

    The US could do with some possession by the spirit of Thomas Edison. He saw things we needed, that were obtainable with years of work from the current technology, and he busted his ass to make them happen. It could be done again. Not everything has to be laid out with every piece pre-discovered before we set out to build something. Where would we be if he had said, "Well, hair doesn't work, and copper wire doesn't work. I guess you can't build a light bulb."?
  • Re:Launch Loop (Score:3, Interesting)

    by ppanon (16583) on Wednesday September 21, 2005 @11:07PM (#13619090) Homepage Journal
    True enough, but Einstein wrote his paper explaining the photoelectric effect fairly close in time to his paper on relativity. The quantization of energy in photons posited in the photoelectric effect paper was a major foundation in the derivation of quantum mechanics, which underlies the understanding of the subatomic required for nuclear fission. And the insight into mass-energy equivalence provided by relativity was useful in convincing researchers that something like fission might be possible since its usefulness in explaining natural radioactivity in elements like radium took a lot less than 28 years. So he's partly got the wrong paper but the argument about timeframes (as he should have presented it) isn't ridiculous at all.

    Of course we don't have a war requiring a substantial portion of USA resources be thrown at making a new bomb, but that kind of support of theoretical and applied research is exactly what is being argued for as well, isn't it?
  • Re:frick n frack (Score:5, Interesting)

    by multiplexo (27356) * on Wednesday September 21, 2005 @11:07PM (#13619091) Journal
    the problem is, tactically, a frickin space elevator is really hard to defend.

    think sept. 11

    Bullshit, 9/11 happened because it was a one off, it's unlikely to happen again because who is going to believe highjackers who tell you that you'll be all right if you cooperate and don't resist. That's not likely to happen again. Also you can set up a no-fly zone for 100 miles or so around the elevator and enforce it with a couple of Patriot missile batteries for distance work and Vulcan cannons for close in work. We have bunches and bunches of people in all four services thinking about ways of improving "if it flies, it dies" technology and they'd love a chance to try out their stuff.

  • by Andrew Price (757340) on Thursday September 22, 2005 @12:22AM (#13619233) Homepage
    Being an SE enthusiast and having presented at two of the SE conferences, perhaps I can provide some useful background.

    The single greatest challenge to building an SE remains that of producing suitable material for its main structural element - the cable.

    A practical Space Elevator requires a material of ultimate strength of at least 50 GPa. Individual nanotubes have been made with several times this strength, but no bulk material has approached it yet. Pure single walled carbon nanotube fibres of length 4mm or greater should produce a spun yarn with strength in excess of 100 GPa and such nanotubes have been produced in 40mm lengths, but not in useful quantities. Steel reaches 5 GPa, but has 4 or 5 times the density of CNTs and so only has a fortieth of the specific strength needed. Aramid fibres such as spectra, dyneema and kevlar come closer, but are only useful for lunar or martian SEs, not earth ones.

    Almost all other issues, such as terrorism / securing the base station / wind / lightning / discharging the ionosphere / lunar and solar tidal effects / atomic oxygen erosion / radiation damage / collisions with the ISS / swarf infall / cyclic heating and cooling / broken ribbon fragments landing on people or damaging the environment etc. either turn out to be insignificant or are fairly easily solved with a little thought and effort.

    The two problems that are harder to solve are: micrometeoroid impact and what has been called 'fratricide' -- where fragments from one SE failing hit other SEs. The likely solution to the micrometeoroid (mm) problem is to make the size and shape of the SE ribbon such that mms do not degrade its strength significantly during the lifetime of the SE. Fratricide is very hard to deal with and will require that ribbons be designed to be VERY unlikely to fail and that they incorporate ways to affect the paths of fragments.

    Beyond these problems there remain numerous areas of investigation such as the fundamental 'mode' or shape of SE to use -- a single straight cable, or a loop, or a straight cable with pieces that are cut from the upper end. Will a material be available that will allow loops or constant-thickness cables (requires 96GPa strength) or must we use a tapered cable? How to design and, crucially, power and cool the climbers -- or will they be 'clingers' on a moving ribbon? But all of these things are engineering design choices, not impediments.

    NASA has been active in funding and encouraging SE research, including several studies by NIAC (by Brad Edwards and Jerome Pearson in particular) and in promoting the Centennial Prizes for tether technologies.

    Given the uncertainty in producing a suitable material, and despite my enthusiasm for SEs I believe that NASA should not yet commit any large budget to the SE, but continue its excellent efforts in promoting the idea through smaller means. It could, however, usefully commit additional funds to CNT research since any progress in high specific strength materials would benefit it even if this research does not result in material strengths useful for an SE.

  • Re:Launch Loop (Score:4, Interesting)

    by QuantumG (50515) <> on Thursday September 22, 2005 @01:56AM (#13619588) Homepage Journal
    On the side where the ribbon comes down you generate electricity which you transfer over to the other side of the structure where the ribbon is going up. That's how you balance the structure without expending a whole lot of energy. The author has been studying this technology for 20 years, along with a lot of other people.. it's solid. There have been scale models built, lots of them.
  • Re:I dont get it... (Score:4, Interesting)

    by Goldsmith (561202) on Thursday September 22, 2005 @03:07AM (#13619743)
    I am a physicist who works in nanotechnology, carbon nanotubes even. I guess I would be one of those physicists who looks through a microscope, and not a telescope. I'm really not sure if you were trying to make a point with that line, but it seems a funny thing to say in a discussion about nanotechnology.

    The things which are coming will blow your mind, but a space elevator with nanotubes isn't happening any time soon, despite what any historians may tell you. Contrary to what the "article" suggests, NASA IS working on this technology. They have spent a huge amount of money trying to get someone to grow a rope of continuous nanotubes just 1 meter long. Some of the best people in the world at nanotube growth are working on this (and have been working on this), and it will take a few years yet before they actually do it. Consider that two nanotubes tied (welded, bound, woven...) together are nowhere near as strong as one continuous nanotube. Consider also that nanotubes grow at around 10^-5 meters/s. Geosynchronous orbit is about 3.6*10^7 meters away. Here, really is the fundamental problem if we're going to try to grow a space elevator. If you go through the math, it would take about 10^5 years with today's technology, which makes the prediction of centuries very optimistic. I think it will take less than centuries (as in, I think we will find new growth or welding techniques), but there may be better ways of getting into space.
  • by drlloyd11 (458569) on Thursday September 22, 2005 @08:41AM (#13620530)
    Oh yeah! Iraq! Remember that? That was gonna be a cheap, novel way to achieve fantastic results if we ignored all those doubters!
        My point is not to simply smear Instapundit, as he does that for himself everyday, but to point out there is a rather large groups of people in the chattering classes out there who beleave EVERYTHING can be solved by an all out push of all resources..
        A war on Cancer/Poverty/Terror/Drugs or some other project to build a huge flipping pyramid of ego.
        This is like when Minsky told a grad student to solve the problem of computer vision on summer break....
  • Re:"Unobtainium" (Score:3, Interesting)

    by Rei (128717) on Thursday September 22, 2005 @01:34PM (#13622925) Homepage
    Please note that your argument about bond strength is a red herring - I never asserted we would figure out a way to make the individual bonds stronger.

    Yes, because you've refused to discuss any potential way at all to make them stronger, and instead have just insisted that "it can be done" without evidence. I was bringing the discussion back to the real world.

    "we have the engineering figured out for using 65 GPa ribbons for a space elevator

    No, we *do not*. We have the engineering figured out for *rare miniscule 63 GPa individual tubes*. Our best bundles are 20 GPa, and that's anything *but* a) long, or B) mass producable. Our best possibly-bulk-producable fabrics are 5-10 GPa - that's orders of magnitude off.

    and we can produce material now that could almost theoretically have that strength

    We cannot. Do not make this false claim again without a cite.

    and in theory we could produce materials almost twice as strong

    If we could magically rearrange atoms to 100% perfect structures for thousands upon thousands of kilometers, it *might* be possible, at best. Short of that.. the word "no" sufficies.

    and I think, this is something that needs research.

    So do I - there is plenty of room for improvement. Lets be realistic, however. I've read what's been coming out of studies on CNTs, and it speaks volumes *against* space elevator-scale bulk materials in the forseable future.

    once we find, say, 30% tougher nanotubes

    How? It's only *theoretically* possible, let alone discovered in practice, that they might be capable of getting that strong. Whether even that is possible is a hotly debated issue. What we know is this: the record is 63 GPa, and most nanotubes tested thusfar are far from that record. What you're asking for means tens of thousands of kilometers of 100% perfect (not a single atom out of place) single type tubes, which is essentially unheard of, and even *that* doesn't guarantee what you want. Essentially all CNTs have *some* errors (due to the process of formation - in both CVD and arc, they're extruded from a condensing sphere of carbon in an inherently chaotic environment), but that's unallowable given what you want.

    and ways to composite them into ribbons 70% as strong as the tubes are individually

    That makes the former problem even more difficult, as it requires either longer tubes (perfectly bundled, at that - another unheard of thing), or intertube bonding (which is, by its definition, defects in the CNTs). It's not a realistic proposal on its own merit; combined with the former proposal, it's preposterous in the "reasonable term". You might as well request a warp drive. People proposing this as a next-gen space launch system are not grounded in the reality of CNT research. It's not realistic for a next-gen system, it's not realistic for the gen after that. Given what we currently know, it's doubtful we'll see it in our lifetime, and is quite possibly outright impossible.

    you assume that we can never do better than our current models of the chemistry and engineering demonstrate

    Propose even a *theoretical* model that will be stronger than nanotube graphene bonds. If not, don't claim anything of this sort again.

    Remember the 9.6kbaud "physical limits" on modems?

    That was more of a math problem than a physics problem. Nobody broke the Shannon Limit - if they had, you might have a point.

    your position seems to be that we've achieved almost all we will achieve with a technology that we didn't even know existed 15 years ago

    Yet, we knew that there was a lot of bond strength that wasn't being realized on bulk in extant materials. In this case, however, we don't have anything theoretically better than what you get from CNTs. You're asking people to invent a way to, literally, perfectly place sextillions of atoms per second, and to do it in the (relatively) short term future. Can't you see how rid
  • Re:New mission (Score:2, Interesting)

    by TallDave (916610) on Thursday September 22, 2005 @08:09PM (#13626111) Homepage
    Yes, but why go back? We're not dealing with any critical life-threatening shortage of Moon rocks afaik.

    There's a good reason we never went back to the Moon: it's a big, airless, resourceless, useless hunk of rock that costs $100 billion to get to. We have rocks here on Earth. They cost a lot less than $100 billion to get to.

All life evolves by the differential survival of replicating entities. -- Dawkins